Hydraulic power rack and pinion steering assemblies for steering a vehicle typically have a cast metal housing. The cast metal housing supports the rack for longitudinal movement to steer the vehicle. The cast metal housing also contains a hydraulic control valve. The hydraulic control valve responds to rotation of an input shaft to regulate the flow of hydraulic fluid to a hydraulic cylinder that moves the rack. Typically, mechanical and hydraulic testing of the assembly occurs after the hydraulic control valve is assembled into the cast metal housing. Assembly problems and hydraulic leaks can occur with the cast metal material of the housing. Hydraulic leaks can also occur through seals that seal the housing. The steering assembly must be disassembled if certain leaks are found. It is expensive and nonproductive to repair the assembly if it must be disassembled due to discovery of a leak, or lack of establishing a correct hydraulic center.
A cast metal housing also has ports through which hydraulic fluid flows between the hydraulic cylinder and the hydraulic control valve. There are constraints on where those ports can be located in a steering assembly, and different steering assembly designs usually require different locations for the ports. The ports are formed in a cast metal housing at predetermined locations when the metal is cast. The cast metal housing can then be used in a steering assembly that requires the ports to be in those locations, but cannot be used in a steering assembly that requires the ports to be in different locations. The manufacturing process for a cast metal housing is thus limited to a particular steering assembly design.